反应详情

To a stirred mixture of the title compound from Example 1 (3.9 g, 0.017 mol), 2,6-dichloropyrazine (10.0 g, 0.067 mol) and tetrakis(triphenylphospine)-palladium(0) (0.05 g) in glyme (ethylene glycol dimethyl ether, 150 mL) was added aqueous 1M sodium carbonate (67 mL), 0.067 mol). The mixture was heated to reflux and for 8 h. After cooling to room temperature, the mixture was poured into brine (300 mL). The layers were separated and the aqueous phase extracted with three 150 mL-portions of ethyl acetate. The combined organic layers were dried (MgSO4) and evaporated. The residue was chromatographed on silica gel eluting with 20% ethyl acetate/hexane to furnish 4.0 g (78% of theory) of the title compound as a white solid melting at 80°-83° C. 1H NMR (300 MHz, CDCl3) δ 10.75 (br s, 1H), 8.91 (s, 1H), 8.51-8.56 (m, 1H), 8.39-8.41 (m,1H), 7.46 (s, 1H), 7.29-7.33 (m, 1H), 2.40 (s, 3H), 1.32 (s, 9H).

1. temperatureThe mixture was heated
2. temperatureto reflux and for 8 h
3. customThe layers were separated
4. extractionthe aqueous phase extracted with three 150 mL-portions of ethyl acetate
5. dry with materialThe combined organic layers were dried (MgSO4)
6. customevaporated
7. customThe residue was chromatographed on silica gel eluting with 20% ethyl acetate/hexane